1. Field of the Invention
The present invention relates to apparatus for shifting, rotating and composing digital information and more specifically relates to such apparatus employing a matrix of bidirectional devices.
2. Description of the Prior Art
Typically, rotations, transpositions, arithmetic and logical shifts have been performed by the use of shift registers, multiplexers and binary ranked shifters. Such devices employ relatively complex circuitry which usually entails comparatively slow operational speeds and large amounts of silicon chip area when fabricated in an integrated circuit.
In order to simplify circuit structure and to increase circuit operational speed, the prior art employs logic matrices having a plurality of columns as inputs and a plurality of rows as outputs. See Perlowski, et al., U.S. Pat. No. 3,818,203. The columns and rows are connected at each intersection by a switching device. The switching devices have typically been grouped into subsets which correspond to the diagonals of the rectangular matrix formed by the input columns and output rows. By selectively writing logical zeroes or ones in various rows and by activating selected diagonals of the switching devices, arithmetic and logical right shifts can be performed in the matrix circuit. The digital information is transmitted through a single device between the input terminals and the output rows.
However, such prior art circuits typically use unidirectional devices, such as junction transistors, so that digital information can move in only one direction through the matrix. Moreover, input information is presented on the columns and then presented on the rows at the next clock pulse. No provision was made for temporarily storing digital information within the matrix circuit. This limitation of prior art matrix circuits limits their ultimate capability to simple rotations and shifts and prevents their application to more complex data manipulations. Furthermore, prior art matrix circuits were typically structured in a rectangular form so that the input columns were substantially at right angles to the output rows. This orthogonal and rectangular topology limits the flexibility by which such circuits may be topologically incorporated into an integrated circuit chip, increases the amount of chip space devoted to such a circuit, and requires the existence of separate regions within the integrated circuit to be set aside for the function performed by the matrix circuit.